The present invention relates to dimensional measurement of objects, more particularly to devices, methods, and systems for performing dimensional measurements of cylindrical objects, for instance performing such measurements for purposes of evaluating compliance of cylindrical objects with engineering tolerances.
Dimensional measurement of cylindrical objects is often difficult and inaccurate. Standard measuring instrumentation (SMI) and coordinate measurement machine (CMM) inspection techniques are widely used to determine whether a part passes or fails precision design criteria. Conventional methods for measuring dimensions of cylindrical objects are often inaccurate, and tend to be difficult, time-consuming, and inconsistent, particularly because of stringent requirements of radial inspection. Dimensional measurement may be critical, for instance, in applications involving cylindrical parts of rockets or missiles, such as rocket tubes or missile tubes.
One conventional approach to measuring the geometric dimensioning and tolerancing (GD&T) requirements of a cylindrical object (e.g. a cylindrical tube, or “CT”) involves implementation of any of various open setups using standard measuring equipment. Measurement of dimensions of components can take, for instance, three hours or more to perform. Another conventional approach to measuring the GD&T requirements of a cylindrical object makes use of a coordinate measuring machine (CMM). This conventional method is time-consuming as well, and requires a highly skilled operator to ensure proper interpretation of the component drawing when writing the CMM inspection program. In addition, a CMM is limited insofar as it cannot properly measure the outer diameter on a long CT, since a typical CMM requires the cylindrical object to be moved during the middle of the inspection process.